2 alternatives I know of;
1/ I have had a speed sensor fitted to my speedo cable by a local automotive instrument specialist. It was only a few hundred dollars including the cost of a new speedo cable. The guy who installed it runs a business in Marayong in the Western suburbs of sydney called MIS (mobile instrument services).
2/ Fit a pulse generator for the number of pulses at about 60km/h. It put's this pulse out whenever the ignition is turned on.
However, this makes the engine think it is constantly doing 60km/h. This can screw with your idle control and stop the engine doing fine tuning on the freeway for good fuel economy.
If you guys can find a cheaper effective alternative, more power to ya! :thumb

the previous message was for subarus as that is what I have, but I think both alternatives are available for other makes of engine (different makes require different numbers of pulses/rev).

Peter, apropros speed sensors, I fitted a reed switch to back of speedo and ajusted it with another magnet to get sensitivity right... seems to work fine and if I can do it, anyone can. I can send instructions if you want; I think I have them saved on comp from "SmallCar" in US...
tony g

Peter, apropros speed sensors, I fitted a reed switch to back of speedo and ajusted it with another magnet to get sensitivity right... seems to work fine and if I can do it, anyone can. I can send instructions if you want; I think I have them saved on comp from "SmallCar" in US...
tony g

thanx for the tip, but my sub is already running

Here's some other ideas.....I got this from a gentleman who lives in Qld.
A great guy who owns another Subi power Transporter. He in turn got this info from someone else and has described what he did to make it work and why....Very helpful I think.

Enjoy......Humpty

____________________

The parts are free (or almost so).

The circuit requires one only component(plus 4 magnets). I used magnets from a disgarded hard drive. They are very much more than adequate. I put four equally spaced dobs of silicone rubber onto the cleaned RHS CV joint. Then I carefully put the magnets on top of the silicone rubber and removed excess silicone rubber. The rubber almost isn't necessary as almost nothing can remove the hard drive magnets once there!

I built a small bracket which I mounted on one of the transmission cover bolts and to which i attahced the competed sensor.

The hall effect sensor requires 12 volts from the battery and sends a pulse to the ECU as required. My advice would be to make up the shielded lead and put a length on sufficiently long to run up into the engine bay and then have a pair of connectors there that connect to ground, power and the ECU input. Encapsulate the IC in epoxy or even silicone rubber and thoroughly cover the connections to the cable. Mount the sensor on the bracket with a couple of cable ties, so it is within a few mm of the magnets. Check that it clears all magnets.

Concerning Reed Relays and magnets.

A friend of mine has worked for 30+ years with Australia's largest telecomunications network. He is an electrical engineer. In telephone exchanges here, Ericson reed switches used to be used and he knew them intimately. He was adamant that I should not use a reed relay.

Consider this. Around town, an average car probably has a wheel rotation of 500 rpm. The EJ22 requires 4 pulses per revolution. This means that the reed relay is operating at 2000 operations per minute.

This means the reed relay would operate 6,000,000 times per 100 hours of driving. The quality of reed switches available here in Australia would be such that they probably have a life of only a few hundred thousand operations if you are very, very lucky. This was why he advised against reed switches.

Given that our VW/Subaru use isn't critical, maybe the simpler reed switch is OK as it can be replaced, but the Hall Effect VSS on file (I have this if anyone is interested - Humpty) will outlive our Subaru engines, I venture to suggest. It is free. It works. It is achievable even by the most feeble-minded (grey-haired) of us. I believe it is also elegant.

I hope this is helpful. I pass the information on with gratitude to both the originator and to the group which has been so very helpful to me.

Dave
downunder.

With full respects to whomever sent me the file.

[Edited on 14-4-2004 by humpty]

GENTLEMAN indeed!!!!

Dave
downunder!

Here is a link to the Toyota training info on VSS

http://www.autoshop101.com/forms/h36.pdf 

Lots of other good info for the EFI newbie http://www.autoshop101.com  look under tech articles

[Edited on 23-4-2004 by Jenny]

I made my own device for driving the Mitsubishi Lancer electronic speedo used in the buggy. First of all hooked the speedo up to a signal generator and recorded the pulses Vs speed readout relationship. Then worked out linear speed Vs roatational speed of the VW speedo cable using the circumference of the VW wheels.

It worked out I need 5 pulses per wheel revolution. So got a plastic circular disc, cut out 5 equally spaced notches and mounted it on the end of the VW speedo cable. A Dick Smith Photo Intterupter was used to sense the notches with a few added biasing resistors. The photo interrupter was then aligned to the spinning disc and screwed down.

Even though you want a pulse for the ECU, you could use the same approach, and it wouldnt matter if it was a bit innacurate.

Good idea ratbug...Nifty solution that one!
As we can see the are plenty of ways to skin this cat!
And Dave......You ain't no gentleman huh?
I can keep your secret!

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